1. Field of the Invention
This invention relates to the field of agriculture, and in particular relates to the treatment of crop seeds, prior to planting, in a low temperature plasma in order to improve the yield of grain, bean and vegetable crops.
2. State of the Prior Art
Known treatments of plant seeds prior to planting include exposure to electric and magnetic fields, electric corona discharge and ultra-violet radiation, to increase germinating power, sprouting rate and yield of the crop.
The effect of static magnetic fields on various crop plants is described in Dayal Sarveshwar, Singh R.P., Effect of the Seed Exposure of Magnetic Field on the Height of Tomato Plants (Indian J. Agr. Sci., 1986, v. 56, #6, pp. 483-486). Seregina M. T. Pavlova N.A., Alymova Z.I., Biological Effect of Magnetic Field on Growth, Development and Productivity of Plants of Winter-crop Grain Cultures (Electronic Treatment of Materials, 1991, #1, pp. 67-71) describes stimulation of metabolic processes and changes in cell membrane permeability, which in turn lead to intensified growth processes and enhanced plant productivity.
Pretreatment of seeds in an electric corona discharge, described in Seregina M.T., Effectiveness of Utilization of Physical Factors during Pre-Plantation Treatment of Potato Tubers/Electronic Treatment of Materials, 1988, #1, pp. 67-74, subjects the seeds to an array of stimuli, including wide-band electromagnetic radiation, ionization, ozone and nitrogen oxides. This particular treatment, however, offers a relatively small zone where a uniform activation effect of the subject seeds is obtainable.
USSR patent No. 211931, class A 01G, 07/04/67, describes exposure of seeds to an ionizing electric field by placing seeds in an inter-electrode space. With a field intensity of 4.5 KW/cm, the yield of rice crops is increased by 8.5%. This method is considered to be insufficiently effective.
According to USSR patent No. 880286 (class A 01C 1/100, A01C 7/04, 11/15/81), seeds are exposed to an electric static field with an intensity of 3-4.5 KW/cm for 5 seconds, 10 days before planting. Then, 5 days before planting, the seeds are again exposed to an alternating current electric field having an intensity of 3-4.5 KW/cm for 5 seconds, resulting in an 18% increase in rice crop productivity.
In USSR patent No. 880287 (class A 01C 1/10, 11/15/81), seeds are treated in a corona discharge field with a field intensity of 4 KW/cm for 3 seconds. The seeds are then treated with 30-40% chlorine choline chloride solution (10-15 liters of solution per 1 ton of seeds). A crop yield increase of 14.6% is obtained, and spoilage resistance is 5 points, compared to 2 points for untreated control samples.
In USSR patent No. 191928 (class A 01C 1/00, 11/26/64), seeds are exposed to electromagnetic oscillations in a solution of microelements, yielding an average 10% increase yield. This improvement is considered low.
In USSR patent No. 660612 (class A 01 1/100, 12/27/77) seeds are heat treated, treated in an electric corona field discharge and soaked in a solution of micro- and macro-elements consecutively. This treatment yields a 26.6% increase in crop yield, but the treatment is complex and multi-staged, and requires use of sophisticated equipment.
Prior methods which attempt activation of plant seeds by exposure to electric corona discharge share a common drawback, namely the non-uniformity of the activation effect obtained on the treated seeds. What is needed therefore is a method for treatment of crop plant seeds which results in large gains in crop yield and uniform results among substantial quantities of treated seed volumes. These shortcomings can be overcome by treatment of crop plant seeds in a low pressure gas electric glow discharge.
A known method of treating wheat seeds in a glow discharge is described by Zahrov V. A., Kresny Y.P. Shchurev A.N., "Effect of Glow Discharge Treatment of Wheat Seeds on Their Water Absorption and Plantation Qualities", Electronic Treatment of Materials 1989, #1, pp. 54-56. According to this reference, seeds are placed on a grid cathode, and the body of the treatment chamber serves as the anode. A glow discharge is generated in residual atmospheric air at between 3-4 Torr pressure and 350-400 V voltage. At a current density of 3 mA/cm2 the treatment time is 30 seconds. Under these conditions, the temperature of the seeds does not rise above 55 degrees Centigrade. The moisture capacity of wheat grains following this treatment is 12%, compared to 10.5% for untreated control grains. Drawbacks of this prior art method include difficulty in maintaining stable conditions so that the temperature of the seeds does not reach 60 degrees centigrade, low efficacy of the process because seed activation occurs only when ions bombard the cathode, and the impossibility of using this apparatus for continuous treatment processes.